New pests threaten B.C. grapes
With the desire for new varieties, the arrival of new pests is inevitable.
The growing movement of goods and people worldwide increases the risk that new pests will invade vineyards in North America and around the world.
“Invasive and new pests certainly pose a serious economic threat to the B.C. grape and wine industry due to increased travel, population growth, and rapid movement of goods and people,” Dr. Tom Lowery, a research scientist at the Pacific Agri-Food Research Centre in Summerland, British Columbia, Canada, said at last summer’s B.C. Wine Institute viticulture conference in Penticton.
An invasive species is typically one introduced to a region and, because of the lack of natural predators or other environmental controls, spreads freely.
Lowery said there were probably about a dozen species that posed a threat to vineyards when the first vines were planted in the Okanagan in the 1860s. A century later, there were 22, and today there are approximately 28 known pests.
The rate of new introductions has increased, Lowery added.
Trade has facilitated the introduction of new pests, he said, but environment-friendly viticultural practices have also played a role. Broad-spectrum pesticides that used to prevent insect intruders from gaining a foothold and spreading are frowned upon. The benefits that softer control measures have had on biodiversity go hand in hand with better chances of survival for new pests.
Moths such as the snailcase bagworm and lesser yellow underwing were identified in British Columbia in the 1980s, for example, while the multicolored Asian lady beetle appeared more recently. The latter isn’t yet the pest it is in eastern North America, Lowery said, where infestations have contributed a distinctive flavor to some vintages of wine. The western grape leafhopper was identified in 1998.
The European paper wasp was identified in 2004 and is now among the wasps most commonly found in the valley, Lowery said. Preliminary indications suggest the species has the ability to bite into grape skins, leaving the fruit vulnerable to yellowjacket wasps, which were a minor problem in the past.
Trade increases risk
Trade in plant material increases the risk of new pests entering the region, Lowery added.
“With the desire for new varieties, the arrival of new pests is inevitable. So we will get new things, but it’s important to prevent or delay the introduction of new pests and minimize the damage they might cause following their arrival,” he said.
New pests may include native species that adapt to grapes, as cutworms did when vines were first planted in the Okanagan, or new, more damaging types of known pests such as phylloxera and blister mites.
A major thrust of pest control efforts is to prevent new species from gaining a foothold. Nationally, Canada allocated $85 million (U.S.$75.5 million) last year to a five-year federal program to fight invasive species.
“We’re most concerned about the introduction of new pests from other regions,” Lowery said. “It is difficult to estimate how damaging an introduced pest is going to be.”
Lowery urged growers to be vigilant against pests such as the grape rust mite, which he said has made inroads in Washington State vineyards.
Regular yellow underwing is another insect that has become a problem in several areas of North America and could also create headaches for growers in the Pacific Northwest.
To limit new pests from cropping up in B.C. vineyards, Lowery urged growers to acquire nursery stock only from reputable suppliers. He also said sourcing nursery stock within regions could help prevent the introduction of new pests.
“If we could produce it here in the Pacific Northwest, we would only have the pests that are here,” he said.